1. Field of the Invention
This invention relates to mechanisms for coupling mower decks to powered vehicles.
2. Description of the Related Art
Many conventional mowers provide a powered vehicle for pushing a mower deck in front of the vehicle for the cutting or mowing of vegetation. Decks are typically coupled with the vehicle via a pair of push arms that extend from the top of the mower deck and connect with the vehicle between the vehicle's two front driven wheels. Large caster wheels are mounted to the front of these decks to support the front portion of the deck above the ground. Conventional push arms are not rigidly fixed to the vehicle, but rather have pin connections with both the deck and the vehicle in order to allow the decks to ride over irregularities in ground conditions. Each push arm can pivot about its connection to the vehicle independent of the other push arm to allow one side of the deck to ride over an irregularity in the ground conditions such as a bump. Therefore, these decks can swing about a plurality of axes parallel with a line defined by the direction of travel.
Many conventional mowers provide decks that are significantly wider than the arrangement of the push arms. Decks that are wider than the push arms and wheel base are advantageous during trimming operations and also act to decrease the size of any uncut circle of grass remaining when the vehicle executes a tight corner. The rear portions of these decks are supported above the ground by connections with the rear portions of the push arms near the center of the vehicle.
As one of the deck's front caster wheels encounters a bump, the caster wheel and the side of the deck on which the caster wheel is mounted will ride up and over the bump. The deck thereby pivots about the other side of the deck's connection with the rear of the push arm. The outer edge of the deck on the side which does not encounter the bump is thereby caused to dip down toward the ground. As the edge of the deck dips down toward the ground, the grass is caused to be cut unevenly. The amount that the edge of the deck will dip is even greater for the wider decks, since the edges of the wide decks extend farther outwardly from the point of connection with the rear of the push arm than do the narrower decks. Therefore, many conventional mechanisms for coupling a deck to a powered vehicle allow the edge of the deck to dip an unacceptable amount, resulting in an uneven cut, and even gouging of the ground.
Some conventional decks provide a gage wheel mounted near the rear outer edge of the deck to prevent the deck and blades from gouging the ground. When operating on level ground these wheels are suspended above the ground. When uneven conditions are encountered the wheels engage the ground as the edge of the deck dips toward the ground and thereby prevent the deck and blades from striking the ground. However, these wheels allow the edge of the deck to dip until the wheel engages the ground. Therefore, the deck is allowed to cut the grass unevenly as the deck dips. It would be possible to fix wheels to the rear of the deck for constant engagement with the ground to thereby establish a point, laterally spaced from the push arm, about which the deck pivots when uneven ground conditions are encountered. Since these wheels would constantly engage the ground, they would have to be larger and more sturdy than the gage wheels that do not constantly engage the ground. It would therefore be costly to mount such a wheel to the rear of the deck for constantly rolling over the ground.
It would therefore be advantageous to provide a mechanism for pushing a mower deck in front of a powered vehicle such that when one side of the deck rises up over a bump in the ground, the corresponding lowering or dipping of the other side of the deck would be reduced. It would be desirable for such a mower to provide for a reduction in the amount of unevenly cut grass and gouging of the ground associated with the dipping of the side of the deck, while not significantly increasing the expense of manufacture for such a deck.